A huge number of solutions exist for effective electrical contact between the leads of an Integrated Circuit (IC) device and a test apparatus. Such an apparatus is used to evaluate performance of the IC device, and to remove from further production those devices that are faulty.
Many of these solutions focus on the configuration of the components used to effect the electrical contact. Because the testing is done at a very high speed, with very high stresses on the components, both electrical and mechanical factors must be considered. Typical considerations include the life span requirements, ease of repairing and replacing components, ease of customizing different configurations, quality of electrical contact, and maintenance.
Manufacturing of IC devices have inherent variations, resulting in variations in the performance of IC devices even within the same batch. It is important for the manufacturer to grade, and subsequently sort, each IC device according to its performance. This will allow the manufacturer to charge a premium for the IC devices that perform better. Hence, it is crucial for the testing apparatus to maintain a non-distorting electrical contact, so that results are as accurate as possible.
One solution for electrical contact between IC devices and testing apparatus is the so called pogo pin design (U.S. Pat. No. 6,506,082). This design has the disadvantage of having to replace the entire electrical contact when it fails. Furthermore, for high frequency testing, where shorter designs are desirable, spring loaded designs need to be wider to maintain a similar spring mass, so there is a compromise between height and finer pitching. Yet another disadvantage of this design is its unsustainable performance under high testing temperatures due to reduction of spring forces at high temperatures.
Another design is the pins within elastomer design (Vaynkof, et. al. U.S. Pat. No. 5,385,477), which is a series of gold particle strains embedded within a compressible layer such as an elastomer. This design has the disadvantage of not being able to make very good electrical contact due to disjoining gold particles. This design also requires the entire mat to be replaced for only a single malfunctioning contact, creating a lot of waste.
Several other designs suffer from downsides such as not being able to be customized by the user onsite, an insufficient current carrying capacity, a high number of components leading to insertion losses, and non-configurable contact forces.
What is needed in the art is an electrical contact that eliminates the afore-mentioned disadvantages.